东山岛海岸带景观破碎化时空梯度分析

运用景观格局指数、缓冲带分析和移动窗口法相结合的方法,分析了福建东山岛18年来从沿海到内陆和海岸地带的景观破碎化梯度变化特征。结果显示:东山岛各缓冲带的景观破碎化程度总体随时间在不断增强,但不同区域有所差异;近海岸地带、西北部及南部的有林地带的破碎化程度持续降低,而中北部和南部城镇农田集中区人为干扰日益强烈,破碎化程度不断增加;采用半变异函数和移动窗口相结合的方法,确定东山岛景观破碎化分析的特征尺度为1000m;在此尺度下,发现景观破碎化指数的变化率随时间存在明显的空间差异,而运用设置样线并提取样点的景观破碎化指数的方法,则发现距离海岸线500m和1000m处的地带破碎化程度不断加剧,是东山岛沿海人为干扰的强烈地带;东山岛人工干扰随时间趋向分散,破碎化指数曲线波动趋向显著;城镇化、旅游和农业发展应该是东山岛景观破碎化的主导驱动因子;采用Pearson相关系数分析景观破碎化与景观格局其他方面特征的相关性,发现它们具有较强相关性,说明运用景观破碎化指数能够反映东山岛景观格局变化的基本特征。

A gradient analysis of coastal landscape fragmentation change in Dongshan island, China

The paper presents the temporal and spatial differences of island landscape gradient change and coastal landscape fragmentation in Dongshan island. Large patch index (LPI) and patch density (PD) were chosen as landscape fragmentation index. Based on remote sensing images of 1994, 2003, and 2011, Dongshan island was divided into 7 landscape types. First, in the landscape classification maps, 26 buffer zones, each being 500m wide, were divided from the coast to inland, then, the landscape spatial patterns of each buffer zone were analyzed with FRAGSTATS. Second, the characteristic scale of landscape fragmentation was determined by using the semi-variable function and the moving window method. Third, according to the determined characteristic scale, moving window method in FRAGSTATS was carried out to analyze the spatial distribution of LPI and PD. Finally, four sample lines, which extend 200m, 500m, 1000m from coastline and across the center of the town were set, and the sampling points for every 200 m were selected on the sample lines, using the sample command of ArcGIS, then, the LPI and PD value of each sampling point were extracted. The results showed that the landscape fragmentation of the buffer zones increased with time generally. The landscape fragmentation continued to decrease in the coastal zones, the northwest and the south zones with forest, while in the town and farmland zones of the island, the fragmentation were increasing. The characteristic scale for analyzing landscape fragmentation of Dongshan island was 1000m. On this scale, it was found that the change rate of landscape fragmentation indicators had obvious spatial difference. Then,landscape fragmentation characteristics of the extracted sample points showed the coastal zone of 500m and 1000m from coastline were disturbed strongly by human, and the fragmentations were growing. The artificial disturbance, which tended to be scattered, created fluctuation significantly of fragmentation index curve with time. Urbanization, tourism, and agriculture development should be the main driving factors of landscape fragmentation. Using Pearson correlation coefficient, we analyzed the correlation of landscape fragmentation and other landscape pattern, which were found to have strong correlation. It indicated that chosen landscape fragmentation index can reflect the basic characteristics of landscape pattern change of the study area.